Wallboard is frequently used as a wall material in home and commercial construction. Wallboard, often referred to as gypsum wallboard, is normally shipped in bundles of two rectangular sheets which are held together by a printed paper tape called bundling tape applied along the edges of the end sheets. The bundling tape is applied to the edges of the two sheets of wallboard at the gypsum manufacturing plant; the tape can either have pre-applied adhesive on the back, or the adhesive can be applied to the back of the bundling tape immediately at the point of application to the wallboard.
Typically, wallboard has a smooth surface on one side and a coarse or tougher surface on the other side. The smooth surface will ultimately face outward into the room where the wallboard is installed. The coarse backing surface is generally tougher, and there is little concern if the coarse back sheet is scratched or nicked in transport. For this reason the bundles are usually formed with the smooth surfaces facing one another and with the rough or coarse surfaces facing outward.
With reference to FIG. 1, a prior art wallboard bundle 115 is illustrated. An upper sheet 117 has its downwardly facing smooth surface facing, and resting upon, the smooth upwardly facing surface (not shown) of lower sheet 119; rough surface 116 on upper sheet 117 is facing upward while the rough surface (not shown) of lower sheet 119 faces downward. Sheets 117 and 119 are generally rectangular in shape, and have side edges 112 and end edges 114. To economize on space in shipping, and to facilitate the formation of bundles, sheets 117 and 119 are arranged so that the side edges 112 and the end edges 114 are co-planar with the edges of the other sheet in the bundle. A small gap 144 may be visible between the two sheets.
Sheets 117 and 119 are fastened together through the use of prior art bundling tape 110 which is applied to end edges 114 and which overlaps onto rough surfaces 116. A zipper tape 111 is placed over the gap 144 when the bundling tape 110 is applied. The bundling tape 110 adheres to the zipper tape as well as to the end edges 114 and rough surfaces 116.
Generally, the zipper tape 111 extends to corners 154 where rough surfaces 116 and end edges 114 meet. Zipper tape (or "zip tape") is generally formed from a roll of "liner board" which is approximately three times thicker than the bundling tape, and which is generally more rigid and stronger than the bundling tape.
The prior art bundling tape 110 is generally an elongated strip of paper, or other suitable material, which may have adhesive pre-coated across its entire bottom surface before application to the wallboard; in the alternative, the zipper tape back surface, the exposed portions of the end edges 114, and the portions of rough surfaces 116 adjacent to corners 154 may all be coated with adhesive so that bundling tape 110 may be adhered to the zipper tape and wallboard. Usually bundling tape 110 is applied at both ends of a bundle to form the complete wallboard package which is shipped.
When a carpenter is ready to use the prior art wallboard package, sheets 117 and 119 are separated by removing zipper tape 111 along with the center portion 134 of the bundling tape 110. To remove zipper tape 111 and center portion 134 of bundling tape 110, the carpenter must grip a first end 140 of zipper tape 111 and pull it away from edges 114; this leaves behind an upper band 132 and a lower band 135 of bundling tape 110. Bands 132 and 135 which remain behind have irregular rough edges 136, and the bundling tape 110 which remains attached to end edges 114 may interfere with the ability to align sheets 117 or 119 with the edge of other sheets or to join closely with flat surfaces. The zipper tape and attached center portion 134 of bundling tape 110 is usually thrown away, although in some cases, it may be recyclable.
The process of producing the prior art wallboard bundles requires special equipment to apply the zipper tape, and then to apply bundling tape over the zipper tape and to the edges and surfaces of the wallboard sheets. Since the zipper tape is approximately three times as thick as the bundling tape, but the rolls of the former and latter usually have equal diameter, it is usually necessary to stop the manufacturing process three times to add new rolls of zipper tape for every one roll of bundling tape. Furthermore, it is necessary to carefully align the zipper tape so that the zipper tape covers the gap between the sheets of wallboard; this is so the bundling tape will not adhere to the end edges 114 in such a fashion that fragments of bundling tape remain across the gap after removal of the zipper tape. If sufficiently large portions of bundling tape remain attached across the gap, the wallboard pieces will not separate; use of a knife or sharp knife or sharp object would then be necessary to cut the bundling tape, and the cutting instrument may damage the wallboard.
The zipper tape is not only more difficult to apply, requiring extra equipment and extra processing steps, but is also more expensive due to the increased amount of material and labor required; zipper tape increases the amount of material which is thrown away and also increases shipping weight. Furthermore, the prior art zipper tape frequently leaves behind portions of bundling tape on the end edges of the wallboard, which require removal in order to facilitate better engagement with an adjacent sheet edge or to reduce the size of cracks in a wall or ceiling.
There is thus a need for a wallboard bundling tape and bundling method which, in some embodiments of the invention, can dispense with the zipper tape of the prior art; yet also be easy to apply and remove, but which is less capable of accidental gluing of the gap between the wallboard sheets in a bundle or which is not capable of leaving substantial amounts of tape on the edges of the wallboard pieces after they are separated. However, other embodiments of the present invention still employ a zipper tape in unique combination with other components or steps, and further include novel apparatus and methods for making and using bundling tape disclosed and claimed herein.